Use is currently made of various kinds of devices making it possible to adjust, on the ski, the longitudinal position of a safety binding which holds the front of a boot (front stop) or the rear of the boot (heel piece) in position. Generally, the heel piece may be moved longitudinally in relation to the front stop mounted in a stationary position on the ski, so as to fit the front stop/heel piece unit to a ski boot of determinate length.
As described in Patents Nos. FR-A-2 451 756 and FR-A-2 614 545, heel pieces are known which, in order to allow adjustment of their position, comprise a longitudinal slide-track attached to the ski, a body mounted so as to slide along this slide-track, and a locking device mounted so as to swivel vertically on the body of the heel piece. This locking device has, on its lower surface, projecting teeth designed to engage in corresponding holes longitudinally aligned in the slide track, thereby forming a rack. The locking device is acted upon elastically, for example by utilizing the return energy of the return spring belonging to the heel piece, such that its teeth tend to become engaged in holes in the corresponding slide-track in the desired longitudinal position. With this kind of heel piece and when modification of its longitudinal position is desired, a tool, e.g., a screwdriver, is engaged in the rear of the heel piece to raise the locking device and cause it to swivel upward, so as to disengage the teeth on the locking device from the holes in the slide-track, thereby making it possible to cause the body of the heel piece to slide on the slide-track. While these devices make possible a relatively simple adjustment of the longitudinal position of the heel piece, they nevertheless have the disadvantage of requiring the use of a tool to perform this adjustment.
Patent No. AT-A-340 293 describes another type of heel piece in which the locking device holding the body of the heel piece in longitudinal position is constituted by the two end pieces, folded transversely toward each other, of an elastic buckle which extends along the slide-track and parallel to it, and beyond the posterior end of the body of the heel piece. This elastic buckle can pivot around the transverse axis given material form by the end two pieces which, by being bent toward each other, constitute locking fingers engaged in the holes in the sides of the slide-track. The body of the binding is released by pivoting the buckle unit upward and forward, this pivoting motion causing, by virtue of the provision of suitable inclined pieces, the end parts of the buckle, or locking fingers, to spread apart and to be released laterally from the holes in the slide-track. While this binding offers the advantage of eliminating the need for a tool for adjustment of its longitudinal position, it nevertheless possesses the disadvantage that the body of the heel piece may be unlocked accidentally when a forward-directed blow struck on the buckle causes the accidental pivoting of this buckle, as often occurs when skis are engaged in bags in the compartments of ski lifts.